[PR88579, patch] Calculating power of powers of two

[Thomas Koenig]

Hi Harald,

> here's my revised patch for the treatment of (2**e) ** n and (- 2**e) **
> n, trying to take into account the bitwidth of the result.
> 
> I've also extended the testcase to sample different integer kinds.
> 
> ChangeLogs see below.
> 
> Note: I don't have commit rights, so please somebody else take care
> of it after review.

Reviewed and committed as r268163.

Thanks a lot!

I see you already sent out a second patch.  We should probably see about
getting you commit rights soon, that should not be a problem.

Regards

	Thomas